Roof Vent Free Area

Ideally the nfa of the soffits should be equal or greater than that of the ridge vent and in no case should the amount of exhaust ventilation exceed the amount of intake ventilation.

Roof vent free area.

Active ventilation products inc. Large 16 1 2 x 16 1 2 in. Made in the usa. Universal dormer vent universal dormer vent 135 sq.

The passive vent net free area table gives the net free area ventilation for some common roof and gable passive vents. Venting products are normally rated with a net free area nfa. Sheet metal manufacturers of roof vents roof exhaust fans and solar attic fans. A normal metal pot vent produces only 50 squares inches of free net area.

Net free area uv 135. So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements. The key to effective venting is to balance air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. Roof vents are made from reliable 28 gauge galvanized steel.

The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation. Build your roof empowers you to select each layer and component that goes into your total protection roofing system so that you get the roof you want to protect your home. Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier. Should you need to add more air intake ventilation to your attic simply determine the number of vents needed from the table based on your net free area requirements.

Balanced ventilation will prolong the life of your roof while providing energy savings and comfort. Two square feet equals 288 square inches. Calculate or enter the square footage of the attic or area to be vented.